May 5: Spring Chinook salmon fishing update

Hi everybody, it is time for my weekly spring Chinook Salmon update (5/5/2020).

Once again we saw very few people fishing for Chinook Salmon last week. The few people we saw were fishing around Lewiston. By last Friday, 312 fish had passed over Lower Granite Dam, so it was not surprising that we did not document any harvest. Based on the number of salmon that are passing over dams downstream on the Snake River, we could see counts at Lower Granite Dam exceeding 500 fish later this week. 

So let’s talk about what the run is looking like. Last week I told you we needed to see counts at Bonneville Dam of over 10,000 adult Chinook Salmon a day to provide a decent fishery. Not only did we not see any daily counts over 10,000 fish, we didn’t see a daily count exceed 3,000 fish (see Figure below). This does not bode well for our fisheries. If you compare what we are seeing this year (red line in graph below) to what we saw last year (yellow line) they are tracking similarly. In fact, from March 1 to May 4 this year, the total count over Bonneville Dam was 18,171 adult fish and for 2019 it was 18,707 fish for this same time period. This is not good as I’m sure most of you realize last year’s return provided little to no fisheries across Idaho. I’ve added counts at Bonneville Dam for 2017 to the figure below as this was one of the latest returns we have ever seen.  If this year’s return has a similar run timing as 2017, that means a fair more spring Chinook Salmon are below Bonneville Dam and we could see a considerable peak sometime this week. If that doesn’t happen, fisheries may close quickly. If you are wondering about the peak in counts during the third week in May in 2017, those were summer run fish destined for places like the South Fork Salmon River and upper Salmon River. Based on the returns of jacks last year to these locations, we are not expecting to see much of a summer run this year. 

counts_over_bonneville_dam_5-4-20
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Joe DuPont

 

To give you a feel for how many of the Chinook Salmon passing over Bonneville Dam are destined for release locations in Idaho and what this could mean as far as harvest shares, I put the table together below.  Since last week, we have had PIT tags pass over Bonneville Dam that are destined to almost all the locations we release spring Chinook Salmon in Idaho. The number of fish that we estimate have passed over as of 5/4/2020 based on PIT tags is shown in the second column. The difficult part is trying to estimate how many more fish are yet to come, and that is all about run timing. I have provided two different run timing scenarios in this table: one uses a 2019 run timing and one uses a 2017 run timing (one of the latest we have ever seen). As you can see, if this year’s run timing is similar to what we saw in 2019, we will not have any harvest share in the Clearwater (-265) and just a little for the Rapid River (214) and Hells Canyon (108) returns. If this run timing is extremely late, like we saw in 2017, we will be able to provide meaningful fisheries on the Clearwater return (2,371) and Rapid River return (5,088). I don’t want to give you false expectations as the data I’ve looked at suggest the run timing is more similar to 2019, but we can always hope.

harvest_share_table_5-5-20
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Joe DuPont

Because there is still uncertainty in how many fish are yet to come, we are not ready to make decisions on whether to shut down any fisheries. By next week, it should be fairly clear on what type of run timing we are experiencing allowing us to make a more informed decision on how to proceed with these fisheries. For those of you worried that keeping the season open another week could cut into broodstock needs, we suspect harvest will be light (fewer than 20 fish) as fish are just starting to get to Idaho.  

That is all I have for you today.  Stay safe and stay healthy everybody.